Ten years ago, more or less, I fitted a pumped power shower. I ran the hot and cold water to the shower unit using 22mm "polypipe" with push-fit fittings. Never a moment's trouble

Until today. One of the push fit joins in the hot water feed suddenly, and for no apparent reason, began to leak, depositing water onto the bathroom and bedroom ceiling. when I pushed the pipes back into the join the leak appeared to stop

About the only thing that I can think of that's changed is that the boiler is out of commission awaiting a replacement and I've been using the backup immersion heater for hot water. I've noticed that the hot water is rather hotter than it used to be, Could that have weakened or pushed apart the join? ShouldI be thinking of replacening the whole thing with copper?

Maybe the coupling is failing? Maybe you didn't push the pipe fully home when it was installed, and it has taken until now to ease out and leak? Maybe it's been weeping for a while and got worse?

You could separate the joint and examine the fitting to see if there is any damage. You could replace that joint.

I wouldn't replace all just because you have had one leak, but I would examine your immersion carefully.

Faulty thermostats cause the water to overheat and boil over into the header tank in the loft which may cause it to fail. You may recall last year a tank failed suddenly pouring boiling water onto a child in the bathroom below.

Thanks. After a day or so to mull it over I came to the same conclusion--I'll start by replacing the join that leaked and keep an eye on it. I picked up replacement connectors for the rest of the installation as well just in case. And some reinforcing inserts; I'm not 100% certain I used them originally; I may have thought I didn't need them for plastic-plastic joints.